139 



also agrees with the two others in the obliquity of the articular faces to the 

 vertical transverse plane of the centniin ; in the present species, these planes are 

 parallel. This species is also larger than the C. iguanavus, Qo^^e; the C. 

 intcrmedius is smaller. 



A smaller specimen, apparently of this species, was obtained by Profes- 

 sor Mudge during his expedition of 1872. The small distal caudals exhibit the 

 coossified chevron-bones, and the articular faces broader than long; the ante- 

 rior caudals do not exhibit the two angular ridges of the lower side, seen in 

 so many species. The lumbars are short, and the dorsals rather elongate, 

 with the slightly vertically-oval articular faces and contracted sides of the 



centrum. 



Measurements (No. 2). 



LeuKth of the centrum (with ball) of the posterior dorsal 0.060 



Depth oftbe cup 0.042 



Width of the cup "-O^O 



Leusthofalnmbar "-040 



Depth of the cup "• f ^^ 



Width of the cup 0-0^7 



Leugth of the caudal without tho diapoijhyses 0.021 



Depth of the cup 0.024 



Width of the cup 0.028 



Length of a more distal caudal - 0. OUt 



Depth of the cup O-O'^Jl 



Width of the cup 0.022 



This is the specimen mentioned under the head of Plesiosaurus gulo as 



having been probably swallowed by the latter. Found near Sheridan, Kans., 



ill the graj' shale. 



SIRONECTES, Cope. 



The characters of this genus are such as to unite closely that wliicli 

 precedes it with that which follows it in the present enumeration. It is 

 more nearly aUied to Platccnrpus in the only species known, where the 

 zygosphen is weak, but articulates with special facets on the lateral walls 

 of the zygantrum, which are not known in that genus. The form of tlie 

 bones of tlie liiuljs is unknown. 



SiRONECTES ANGULIFERUS, Cope. 



Established on a portion of the left mandible, with a series of thirty-one 

 vertebioe, of a single individual, discovered by Prof B. F. Mudge in the gray 

 calcareous shale of Trego County, Kansas. 



Some of the vertebrae have suffered from pressure; but the centrum 



